import java.lang.reflect.*;
import java.util.*;

/**
 * Created by ScorpionOrange on 2016/10/16.
 */
public class GenericReflectionTest {
    public static void main(String[] args){
        // read class name from command lines args or user input
        String name;
        if(args.length > 0) {
            name = args[0];
        }
        else {
            Scanner in = new Scanner(System.in);
            System.out.println("Enter class name (e.g. java.util.Collections): ");
            name = in.next();
        }

        try{
            // print generic info for class and public methods
            Class<?> cl = Class.forName(name);
            printClass(cl);
            for(Method m : cl.getDeclaredMethods()){
                printMethod(m);
            }
        }
        catch (ClassNotFoundException e){
            e.printStackTrace();
        }
    }

    public static void printClass(Class<?> cl){
        System.out.println(cl);
        printTypes(cl.getTypeParameters(), "<", ", ", ">", true);
        Type sc = cl.getGenericSuperclass();
        if(sc != null){
            System.out.print(" extends ");
            printType(sc, false);
        }
        printTypes(cl.getGenericInterfaces(), " implements ", ", ", "", false);
        System.out.println();
    }

    public static void printMethod(Method m){
        String name = m.getName();
        System.out.print(Modifier.toString(m.getModifiers()));
        System.out.print(" ");
        printTypes(m.getTypeParameters(), "<", ", ", ">", true);

        printType(m.getGenericReturnType(), false);
        System.out.print(" ");
        System.out.print(name);
        System.out.print("(");
        printTypes(m.getGenericParameterTypes(), "", ", ", "", false);
        System.out.println(")");
    }

    public static void printTypes(Type[] types, String pre, String sep,
                                  String suf, boolean isDefinition){
        if(pre.equals(" extends ") && Arrays.equals(types, new Type[]{Object.class})){
            return;
        }
        if(types.length > 0) {
            System.out.print(pre);
        }
        for(int i = 0; i < types.length; i++){
            if(i > 0) {
                System.out.print(sep);
            }
            printType(types[i], isDefinition);
        }
    }

    public static void printType(Type type, boolean isDefinition){
        if(type instanceof Class){
            Class<?> t = (Class<?>) type;
            System.out.print(t.getName());
        }
        else if(type instanceof TypeVariable<?>){
            TypeVariable<?> t = (TypeVariable<?>) type;
            System.out.print(t.getName());
            if(isDefinition){
                printTypes(t.getBounds(), " extends ", " & ", "", false);
            }
        }
        else if(type instanceof WildcardType){
            WildcardType t = (WildcardType) type;
            System.out.print("?");
            printTypes(t.getUpperBounds(), " extends ", " & ", "", false);
            printTypes(t.getLowerBounds(), " super ", " & ", "", false);
        }
        else if(type instanceof ParameterizedType){
            ParameterizedType t = (ParameterizedType) type;
            Type owner = t.getOwnerType();
            if(owner != null){
                printType(owner, false);
                System.out.print(".");
            }
            printType(t.getRawType(), false);
            printTypes(t.getActualTypeArguments(), "<", ", ", ">", false);
        }
        else if(type instanceof GenericArrayType){
            GenericArrayType t = (GenericArrayType) type;
            System.out.print("");
            printType(t.getGenericComponentType(), isDefinition);
            System.out.print("[]");
        }
    }
}
